MISS EMBLETON ON CEEATAPHIS LATAKI^. 99 



generations, resulting in the production of a winged sexual form 

 in cases where winged individuals have previously occurred in the 

 cycle of generations. The life-history of CeratapTiis lataniee is 

 very different from that of the Coccidce. 



This insect has now been under observation for more than 

 a year in Cambridge, and though the investigation has been of a 

 somewhat desultory nature, owing to the lack of a special labora- 

 tory in which to pursue such work, yet nothing has been found 

 to suggest in any way that the conditions of form and development 

 mentioned above have been departed from by any individuals. 

 Specimens have been collected from time to time by Miss M. A. 

 Sharp and myself, and submitted to examination with a view to 

 ascertaining whether any diversity, other than that of age, could 

 be detected among them, but we have failed to find any indication 

 of such diversity. Moreover, all figures and records that exist 

 of the insects in this country exhibit it in this form only. 

 Westwood's figures of the specimens obtained from Dublin in 

 1879 show the young and adult forms as we have them now at 

 Cambridge. Buckton's figures and remarks give evidence of the 

 same uniformity. 



All the observations, then, that hare been made in this country 

 lead to the belief that the species exhibits here only one form whicb 

 reproduces partlienogenetically in an uninterrupted manner. 

 Parthenogenesis extending over a variable number of generations 

 is, of course, a very common occurrence among Aphides : and it is 

 probable that even in climates (such as the Isle of Bourbon, 

 Brazil, &c.) where the winged females of this species are pro- 

 duced not infrequently, that it is still an important, if not an 

 exclusive, mode of perpetuating the species. No males have yet 

 been discovered anywhere. E-emarkable as this fact is, it is not 

 without parallel, but it is extremely unusual for this mode of 

 reproduction to be the concomitant of a metamorphotic ontogeny 

 repeated uninterruptedly from generation to generation. It is 

 possible that the parthenogenetic reproduction of Aphides can be 

 carried on for a great number of generations ; indeed, such 

 continuity has been shown to exist, though its limits have not 

 yet betn determined. 



Gerataphis latanics in this country appears to be entirely 

 deprived of the complex life-history found in its allies (on which 

 I shall subsequently enlarge). In the Cambridge Natural 



